In recent years, with rapid development of mobile Internet, a requirement of a mobile user on system capacity is increasing, and shows a trend to exponential increase. Due to a using characteristic of an unlicensed spectrum, that is, multiple sets of systems or multiple pieces of equipment need to compete for a channel using right, the channel using right is shared between the systems or the device in a time division manner. After a Licensed Assisted Access (LAA) base station obtains the channel using right, there may exist a phenomenon that occupancy of an LAA system over a channel cannot be effectively identified and an opposite end further cannot rapidly determine a channel occupied by the LAA system because a signal sending starting time point is at a middle location of a sub-frame, particularly the signal sending starting time point is at a middle location of an Orthogonal Frequency Division Multiplexing (OFDM) symbol, which influences a user experience for the LAA system.